Air diffuser



United States Patent C i AIR DIFFUSER Harry I. Walpole, Leonia, N. E.

Application October 7, 1954, Serial No. 460,895

8 Claims. (Cl. 98-4t}) which are variants of several general types of diffusers.

For example, there are many modifications of diffusers based on the venturi principle while othersemploy fixed and variable deflectors and baffles.

The venturi type of air diffuser, by nature, increases the velocity of entering air above the velocity of the air in the duct and hence creates an air draft condition in the chamber that causes cold spots in the region immediately below the diffuser. In the conventional baffle type diffuser, a complicated arrangement 4of deflecting plates is used that be re-adjusted when the duct air flow increases or decreases for any reason.

It is an object of the present invention to provide a diffuser for mixing entering air with chamber air inV a must be adjusted carefully for best operation Vand must manner to minimize sharp temperature gradients and drafts in a chamber to be ventilated.

lt is a further object of the present invention to provide a diffuser for mixing entering air with lchamber air which needs no adjustment in order to mix the entering and chamber air without local drafts and sharp temperature differentials. Other objects of the present invention include the provision of a diffuser of relatively large size with respect to the air duct, which diffuser is contoured and dimensioned to facilitate the diffusing of entering air with chamber air in silence and without local drafts and uncomfortable temperature zones 0r areas.

Other objects of the present invention will be appreciated upon a study of the following specification together with the accompanying drawings, in which,

Fig. 1 is a plan view from the normal bottom of one embodiment of a diffuser illustrating the present invention, with parts broken away for clarity, and

Fig. 2 is a cross-sectional view of the diffuser taken along the line 2 2 of Fig. l, showing the diffuser mounted on an air duct.

Referring to Figs. 1 and 2 which illustrate one embodiment of the invention, there is shown the main body of the diffuser which comprises a circular plate 10 of cast metal such as aluminum having a central hub portion 11 to which a transverse supporting rod 12 is attached by having its lower end threaded and screwed into threaded hole 13. The top of rod 12 is threaded to a spider member 14 mounted within an air inlet duct 15 by means of fasteners such as studs -or screws 16 fastened through bracket arms of the spider 14 to the wall of air inlet duct 15.

Plate 10 is slightly dished from the rim inwardly toward the hub portion 11 and the upper or duct-facing side of plate 10 has formed thereon two annular baffles or fins 17 and 18 which intersect with radially extending stiffen- 2,796,821 Patented June 25, 1957 rice ing' ribs 20, of which there are eight in the embodiment of the invention illustrated.

. Radiallyvinwardly of each of the annular fins 17 and 18 there are formed concentrically extending slots 21 and 22, respectively. These slots are interrupted only by small web sections at each radial rib 20, as is clearly shown in Fig. 2.

Immediately below the slots 21 and 22 are baffle rings 23 and 24, respectively,l which are mounted to, but spaced from, thelower surface `of plate 10 by a series of pins 2S.

The diffuser is suspended below theduct 15 at a fixed distance from the chamber ceiling 26, which distance is determined at the time of installation and need not thereafter be varied.

ItV will be noted that the diffuser shown in the drawings has an area many times greater than the area of the air duct 15. The general pattern of airflow is indicated in Fig. l. Air entering the chamber from duct 15 strikes the dished central portion of the diffuser plate 10 and is deflected radially outwardly, striking in turn the annular fins 18, then 17, which induce turbulence in the air stream, creating an'ideal condition for the quicker admixture of entering and `chamber air. As the air moves radially outwardly, its velocity decreases because of the fact that the air is being distributed over an area many times that ofduct 15, so that, vas the air starts spilling over the outer edge of plate 1f), its velocityhas dropped considerably, minimizing local drafts in the chamber in the area of the diffuser.

A very small portion of the entering air flows through r the slots`21 and 22 and mixes with the chamber air immediatelyV below the diffuser plate 1t). The air flowing through` these slots is deflected radially in turn by deflecting rings 23 and 24 so that the admixing of entering and chamber a'ir is accomplished :close to the lower surface of diffuser plate 10, thus minimizing sharp temperature gradients below the diffuser at head level of the occupants of the chamber. It should be noted that the same beneficial effect is obtained with respect to air spilling over the outer rim of plate 10. The velocity of the entering air being at a minimum, and the area being large compared to the air duct area, admixture is accomplishedradially outwardly of plate 10 lin a region close to the lceiling 26, so that air drafts'and sharp temperature gradients do not exist at head level in the chamber.

The embodiment of the invention set forth above is preferably made of a light cast metal such as aluminum, however it will be understood that the diffuser may be cast, molded or otherwise fabricated of any metal, plastic or other material according to the size, cast and decorative requirements. The use of two annular baffles inclined from the vertical at an angle of about 30 degrees, as shown, together with the -dish-shaped plate 10 is particularly desirable and has resulted in an extremely efficient air diffuser which has the ability to deliver and diffuse large volumes of air with no drafts or noise. This preferred form may be varied by changing the shape of plate 10 and the number of annular baffles while still obtaining the advantages of the new diffuser form. Thus a generally flat plate with a square outline with one or more baffles will provide a less ecient but satisfactory action where slight air movements in rooms is not objectionable. Similarly where the supply of `air without drafts immediately below the diffuser is not important, the number and position of the circular slots may be varied to provide the amount of air desired.

It will be seen that the present invention provides an air diffuser which will admit a large volume of air to a room to replace or refresh the air therein without creating -air movements within the room. The diffuser is also quiet in operation. The device is relatively simple and is easily constructed and mounted. There are no moving 3 parts and no adjustments are required after the diffuser has been put into place.

As various changes may be'made in the form, construction and arrangement of the parts herein without departing from the spirit and scope of the invention and without sacrificing any of its advantages, `it is to be understood that all matter herein is to be'interpreted as illustrative and not in a limiting sense. Y

Having thus described my invention, I claim:

1. A device for eecting the diffusion of anfentering air stream into a chamber through a duct opening comprising in combination a circular diffusing plate to be spaced from said opening and having one face for mounting toward the entering air, said circular plate having an area many times greater than the area of said opening, said plate being dished concavely on said face at its center portion and said plate having a plurality of rows of radially spaced, upstanding bafes on saidfaee.

2. A device for eecting the diiusion of an entering air streamrinto a chamber through a duct opening comprising in combination-a circular diffusing plate to be spaced from said opening and having one face for mounting toward the entering air, said circular plate lhaving an area many times greater than the area of said opening, said plate being dished concavely on said face at its center portion, said plate having a plurality of rows of radially spaced, arcuately extending slots therethrough, and each of said arcuately extending slots having an upstanding baffle on its radially outermost edge.

3. A device as set forth in claim 2 further comprising a series of annular deflecting rings suspended from said plate under each of said rows of slots and spaced therefrom. e

4. A device for effecting the diffusion-of an entering air stream into a chamber through a duct opening comprising in combination a circular diffusing plate to be spaced from said opening and having one face for mounting toward the entering air, said circular plate having an area many times greater than the area of said opening, said plate being dished concavely on said face at its center portion and convexly at its center portion on its opposite face, said plate having a plurality of rows of radially spaced, arcuately extending slots therethrough, and each of said arcuately extending slots having an upstanding bathe adjacent to its radially outermost edge.

5. A device as set forth in claim 4 further comprising a series of annular deiiecting rings suspended from said plate under each of said rows of slots and spaced therefrom.

6. A device for efr'ecting the diffusion of an entering air stream into a chamber from a duct opening comprising a generally flat diffusing plate having one face for mounting spaced from and facing the duct opening and generally at right angles to the direction of air ow from the duct opening, said plate having an area substantially greater than the duct opening, an -upstanding baieon the duct-facing surface of said plate describing a closed path and spaced from the center of said plate, and an aperture in said plate spaced outwardly from its center portion adjacent to said baffle and Within the area described by said bale.

7. A device for effecting the diffusion of an entering Y air stream into a chamber from a duct opening comprising a generally flat diffusing plate having one face for mounting spaced from and facing the duct opening and generally at right angles to the direction of air ow from the duct opening, said plate having an area substantially greater than the duct opening, an upstanding baille on the duct-facing surface of said plate ldescribing a closed path and spaced from the center of said plate, and an elongated slot in said diffusing plate adjacent to said baie and generally parallel thereto and within the area described thereby.

8. A device for effecting the diffusion of an entering air stream into a chamber from a duct opening comprising a generally dat diffusing plate having one face for mounting spaced from and facing the duct opening and generally at right angles to the direction of air ow from the duct opening, said plate having an area substantially greater than the duct opening, an upstanding circular baille on the duct-facing surface of said plate describing a closed path and spaced from the center of said plate,

and an arcuate slot in said dilusing plate generally parallel to said baffle.

References Cited in the le of this patent UNITED STATES PATENTS Germany Mar. 9, 1938 

